There's only one dietary "science" that has real credibility. A balanced decrease in calories and exercise.
I think this will change with time. "Confirmation bias" seems to have ruled the day since the 1960s or so.
Personally, I have been eating high-fat and low-carb for a number of years now. Not anything formal like the Atkins Diet, but just a recalibration of my views on what I ought to eat. By "high fat", I mean that I pay no attention to the amount of fat that I am eating, and try to keep carb consumption low. My wife notes that we go through a pound of lard per week
Funny thing is, I'm unquestionably healthier now than I was when I was eating a so-called "balanced diet." There's really no explanation besides my decreased carb intake. Even my (initially skeptical) doctor is happy with the results.